Alright, while many claim that with his undeniably impressive feats, Batman would win easily, but I don't believe that he would be well matched against a Guardian. First of all, let's talk weapons and abilities. Batman's armor can easily resist the small arms, and even assault class weaponry of the 21st century, but it wouldn't be very useful against the weapons Guardians use. Most of their ballistics use programmable digital matter, though some involves ionized plasma and energy weapons of the sort. Batman's gun-proof suit and heat insulator would be no match against such weaponry, and we haven't even begun to discuss supers yet. Now, a Nova Bomb is stated in the Grimoire to posses the energy of an exploding star (in gameplay this isn't so, and scientifically this would be impossible, but this is the only evidence that we have right now, so it must be considered canon). Batman would be completely disintegrated by such a blast. I'm too lazy to recall the Grimoire for the other supers, but similar results would ensue. Now, you could make the argument that Batman would never reveal himself in the first place, hiding in the shadows or ambushing the Guardian, but that is merely circumstantial, and can also be countered. Next up on my list of arguments is Melee, Strength, and Intelligence. Batman is a human in almost peak physical state, and possesses a genius level intellect, but the Guardians outclass him in almost every category. First of all, Guardians can live for hundreds of years, as evidenced by the fact that the Traveller can greatly extend lifespans. That means that they would have decades more experience in CQC and firearm training, alongside honing their abilities. A Titan would utterly destroy Batman up close, let's be realistic. Batman has only survived so many encounters against superhuman foes due to plot armor, but would he win a fight against a being who is better armored, trained, far stronger and faster, and has the power of the light? The answer: almost certainly no. Warlocks also have the ability to disintegrate armored foes with their melee attack, so if batman came close to them... Yeah. Also, as smart as Batman is, Warlocks posses light augmentations to their brains, allowing them to surpass regular human limitations as far as intelligence goes. They would be like the Taskmaster, predicting Batman's moves before they were put into effect. And look, I'll admit, Batman has beaten some foes that Guardians couldn't hope to, but that was due to the fact that most had one deadly weakness that he could exploit. Guardians have none. Now, all of this is circumstantial, but I can't see a way in which Batman would win a fight against a Guardian. Therefore, in conclusion, I believe that Batman would win.

Batman always has access to the latest weapons and tech. Guardians are stuck using old ascended weapons. Batman for the win. Plus Batman already beat Superman. Enough said.

Batman would hack in Destiny and lag out all the servers, or he would find you and kill you

Batman has prep time while the guardian is loading in orbit for 20 freaking minutes.

Who says my guardian isn't Batman? Could be the reason my ghost chose me.

Look, Batman would adapt and beat each Guardian over and over, but he would never kill them. So if it's a fight to the death, it's an auto win for Guardians

If Batman can beat Superman, he can surely beat a Guardian.